Article 50 -Escalators & Moving Walks Stopping Devices
Requirements of Escalators and Moving Walks Stopping Devices
The emergency stop button which is actuated manually has to be shown in red color (AKA Stopping Devices) or be marked by the sign “STOP” which is projected from the device or in the vicinity of it. The aforementioned requirement is not met while emergency situations when the escalator or moving walk ceases operation as the actuator of the stop device is activated. It is of utmost importance as to where the stop device shall be positioned which is required to be easily visible as well as reachable close to each landing of the escalators and moving walks. At the threshold of landings, stop switches must be at reach from outside the step/pallet band.
The below-mentioned characteristics should be attributed to the stop switch if it is situated in the vertical distance between the handrail and step nose or pallet/belt surface at the lower part of the balustrade:
- The Stopping Devices must have a minimum diameter of 80 mm;
- It must be colored red;
- It must be marked with “STOP” in white letters;
- It must be located above half the balustrade height in the vertical distance between the handrail and step nose or pallet/belt surface;
- There must be an arrow - which may also be located in the vertical distance between the handrail and step nose or pallet/belt surface at the lower part of the balustrade - pointing from the sign towards the stop device.
Stop devices should not be far away from one another more than 30 meters for escalators and 40 meters for moving walks. Extra stop switches must be provided in case the distance is needed to be maintained.
Moving walks, which are intended to be used for the conveyance of trolleys and baggage carts, considering extra devices for emergency cases is necessary. For those stop devices close to transition curves, accessibility from inside is obligatory and the ones at the exit(s) have to be reachable from outside the moving walk.
Emergencies’ stop devices must operate by positive mechanical separating of the contacts. This separation must take place even if the contacts are welded together.
Positive mechanical separation is done in absence of no elastic elements such as springs between the moving contacts and the part of the actuator to which the actuating force is applied, while all contacts are at their open position. The risk of short-circuit resulting from an erroneous component is minimized by appropriate design.
According to EN 60529:1991, provided that the enclosure causes a degree of protection of at least IP 4X, a safety switch must be devised for a rated insulation voltage of 250V. In addition, if the degree of protection of the enclosure is less than IP 4X, the safety switch must be provided for a rated insulation voltage of 500 V.
According to EN 60947-5-1:200410, safety switches must belong to the following categories:
- a) AC-15 for safety switches in alternating current circuits;
- b) DC-13 for safety switches in direct current circuits.
The protective enclosure must be at least of type IP 4X, or else the air gaps have to be considered 3mm and 4mm respectively. In addition, the distance for contacts after separation must be at least 4mm.
If there are multiple breaks, the individual distances for breaking contacts after separation must be at least 2 mm.
The remainder of the conductive material shall not lead to short-circuiting of contacts.
NOTE: With regard to EN ISO 13850:2015, manually operated stop devices in emergency situations do not support the functional requirements. Therefore, emergency stop switches for the specific purpose of safety for escalators and moving walks are defined differently in comparison to EN ISO 13850:2015.
Different Types of Stop Devices Installed in an Escalator
There are about thirteen safety stop devices installed in an escalator or a moving walk in general, and each of them is used to stop the escalator or moving walk during emergency situations and prevent disastrous hazards. The stop devices installed in escalator and moving walks are as the following:
1.Emergency stop button
A stop button that stops the escalator or moving walk instantly in emergency situations.
2. Electromagnetic Brake
A device that stops the escalator or moving walk in the time of power outage or when the emergency stop button is activated.
3. Step Motion Safety Device
A safety device that stops the escalator if an object is trapped between the steps or step and skirt brush and a step is jutted out, or when there is an anomaly seen in the step motion.
4. Drive Chain Safety Device
A safety device that stops the escalator in case the drive chain is broken or is extended more than it is supposed to.
5. Reversal Stop Device
A safety device that stops the escalator if there is a sudden and remarkable decrease or increase in the escalator rated speed.
6. Step Level Device
A device that stops the escalator in case the horizontal level of a step is dropped.
7. Overload Detector Device
A safety device that stops the escalator if it detects any overload through an unusual current or temperature of the drive motor.
8. Handrail Speed Detecting Device
A safety device that stops the escalator if it detects the handrail’s speed has exceeded the rated speed due to slippage, loosening, or breakage of the handrail.
9. Skirt Brush Safety Device
A safety device that stops the escalator in case any foreign object such as shoes are trapped in the gaps between the steps and skirt brush.
10. Comb Plate Safety Device
A safety device that stops the escalator if a foreign object is trapped between the comb plate and a step.
11. Handrail Inlet Guard
In case the handrail inlet guard is pushed by a foreign object or in case any object gets suck in the inlet guard entrance, it actuates the handrail inlet switch and stops the escalator.
12. Step Chain Safety Device
A safety device that stops the escalator in case of detecting a breakage in the step chain.
13. Missing Step Safety Device
A safety device that stops the escalator when there’s a missing part of steps before it is observable by passengers.